The invention relates to facilities for transforming the internal cross-section of a thin-walled pipe or other cylinder into a non-circular, symmetrical closed form. More particularly, the invention relates to apparatus of such type which performs the required working of the pipe while the pipe is axially advanced in a first direction.
In previous techniques for converting a round pipe into other suitable shapes (such as rectangular, flat-oval and the like) useful for applications as air-conditioning ducts, cable protectors, etc., it has been common to provide cooperating internal and external jaws which are suitably positioned and configured to distort discrete sections of the pipe into the desired shape. In such arrangements, the jaws are hydraulically of pneumatically actuated.
Such arrangements have the disadvantage of being extremely bulky and heavy, as well as expensive to run and maintain. Additionally, it is difficult and cumbersome to interchange the operating jaws to accommodate different types of final, non-circular cross-sections, and in any event are adapted to handle only relatively short sections of pipe.